git: 8dc4c0a922b7 - stable/12 - net80211: correct length check in ieee80211_ies_expand()

The branch stable/12 has been updated by emaste:

URL: https://cgit.FreeBSD.org/src/commit/?id=8dc4c0a922b7e7a0ee682f4e1426f876692c0828

commit 8dc4c0a922b7e7a0ee682f4e1426f876692c0828
Author:     Bjoern A. Zeeb <bz@FreeBSD.org>
AuthorDate: 2021-10-06 18:09:39 +0000
Commit:     Ed Maste <emaste@FreeBSD.org>
CommitDate: 2022-02-14 22:00:13 +0000

    net80211: correct length check in ieee80211_ies_expand()
    
    In ieee80211_ies_expand() we are looping over Elements
    (also known as Information Elements or IEs).
    The comment suggests that we assume well-formedness of
    the IEs themselves.
    Checking the buffer length being least 2 (1 byte Element ID and
    1 byte Length fields) rather than just 1 before accessing ie[1]
    is still good practise and can prevent and out-of-bounds read in
    case the input is not behaving according to the comment.
    
    Reported by:    (coypu sdf.org)
    admbugs:        857
    MFC after:      3 days
    Reviewed by:    adrian, markj
    Differential Revision: https://reviews.freebsd.org/D32340
    
    (cherry picked from commit 09dd08f167812a5fdb516fc98f14dbb43221432f)
---
 sys/net80211/ieee80211_node.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/sys/net80211/ieee80211_node.c b/sys/net80211/ieee80211_node.c
index 9ee5b1b83cde..36dfea039df1 100644
--- a/sys/net80211/ieee80211_node.c
+++ b/sys/net80211/ieee80211_node.c
@@ -1134,7 +1134,7 @@ ieee80211_ies_expand(struct ieee80211_ies *ies)
 
 	ie = ies->data;
 	ielen = ies->len;
-	while (ielen > 0) {
+	while (ielen > 1) {
 		switch (ie[0]) {
 		case IEEE80211_ELEMID_VENDOR:
 			if (iswpaoui(ie))